Jack O’Connell – see his star-making performance in outstanding prison drama Starred Up before headlining Angelina Jolie’s POW-biopic Unbroken – in addition to being one of the most beat-up on-screen actors in the business, is also one of the most promising actors of his generation. He is sensational again in urban war thriller ‘71, the début feature from filmmaker Yann Demange, who won Best Director at the 2014 British Independent Spirit Awards. It is also the first feature screenplay from veteran Scottish playwright Gregory Burke. The civil tension that tore apart 1971 Belfast is brought to life in brutal, authentic, unflinching fashion in this tight, gripping film that balances historical truth with formal audacity.

O’Connell stars as Gary Hook, a young British soldier who has graduated from a foster care youth into a cog in a squad rerouted from their intended deployment in Germany to Belfast in 1971, when the city was at the peak of conflict. On the first day, the squad are assigned to inspect houses for firearms on Divis Street, a volatile area of Belfast where Catholic Nationalists and Protestant Loyalists live side by side. Things get worse than the youth-pelted urine bombs, and when their presence is made known the street is soon filled by an angry Catholic mob who soon overpower the unit. Hook, having pursued a young boy who stole a stray gun through the streets, is left behind following the retreat and forced to fend for himself.

Hook later stumbles across a young Protestant boy who brings him to a local pub, where he meets a member of the undercover Military Reaction Force, working with the Loyalists. He makes contact with fellow MRF’s, who set in motion a plan to rescue him. From there, Hook experiences all kinds of trouble, requiring the help of strangers (including a Catholic ex-medic and his daughter) who are wary of making their assistance known to the relentless IRA street fighters on the hunt for Hook. But we soon learn that even those assigned with the safe recovery of Hook have other agendas, and Hook understands that he cannot trust anyone.

From what I had heard about ‘71, I expected to see a lot of O’Connell on screen solo, trapped in hostile territory and on the run from the IRA. That is true, but the strong cast runs surprisingly very deep, populated by veterans who bring plenty of class to the film, and is particularly interesting for anyone that has seen Calvary. Richard Dormer (Game of Thrones), Paul Anderson (Peaky Blinders), Sean Harris (The Red Riding Trilogy), David Wilmot and Killian Scott (Calvary) and Sam Reid (Belle) portray just some of the characters that cross paths with Hook. O’Connell has become known for portraying tough-skinned characters who go through intense physical and emotional stress – and he is incredibly convincing at it. He spends a large part of this film covered in blood and favouring debilitating injuries. A real feat of physical acting from the young man.

The score from Irish electronic musician and Soderbergh-regular David Holmes is brilliant work, while the heavy use of hand-held is very effective, and matches the manic intensity of Hook’s situation, immersing us in the warfare as a too-close-for-comfort observer. As Hook is driven into Belfast there is an aerial shot of the city that is out of focus, giving the place a haunted spectral quality, signifying that evil is lurking here and it could be behind any door. Sometimes the camera adopts Hook’s personal POV, but he is ultimately just a piece of the film’s focus. The recreation of the war-torn city is very convincing, and the way that opening riot sequence is shot is jaw-dropping in its realism. The thrilling cat-and-mouse gauntlet within a multi-story apartment block was the film’s highlight for me, as a severely injured Hook attempts to elude his pursuers.

The film’s forgivable flaws come through its narrative; which is very attentive in trying to include all of the politics and conflicts of the period – inner-workings and hierarchy of the IRA, disillusionment of the youth drawn into the struggle, corruption within the authorities, and the double-crossing that meant there was a cloud of unease at all times. While there are quite a few characters explored, in its attempt to fit in so much, some of them are left short of motivation and their actions seem abrupt.

‘71 is a real edge-of-your-seat manhunt thriller, capturing the internal ugliness of the Irish-British struggle, and wrapping it all up with a devastating finale.